As for the inconsistency between the bodies arrival and Sayid's arrival to the island (which has yet to take place)...I think it will have to do with a difference in the bearing they follow. Sayid is following a bearing of 305 which according to my theory would minimize the freighter/island time difference. The dead floating body would be following who knows what bearing. Whatever bearing it followed must have caused it to arrive at a different time...days before in fact. This definitely goes to support my theory that the bearing is not as important to where you arrive as WHEN you arrive.